from __future__ import absolute_import

from django import forms
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.core.serializers.json import DjangoJSONEncoder
from django.utils.encoding import force_text
from django.utils.functional import Promise
from django.utils.html import conditional_escape
from django.utils.safestring import mark_safe
from django.utils.translation import get_language

from js_asset import JS, static

from .configs import DEFAULT_CONFIG

try:
    # Django >=1.11
    from django.forms.widgets import get_default_renderer
except ImportError:
    # Django <1.11
    from django.template.loader import render_to_string

    def get_default_renderer():
        class DummyDjangoRenderer(object):
            @staticmethod
            def render(*args, **kwargs):
                return render_to_string(*args, **kwargs)

        return DummyDjangoRenderer

try:
    # Django >=1.7
    from django.forms.utils import flatatt
except ImportError:
    # Django <1.7
    from django.forms.util import flatatt


class LazyEncoder(DjangoJSONEncoder):

    def default(self, obj):
        if isinstance(obj, Promise):
            return force_text(obj)
        return super(LazyEncoder, self).default(obj)


json_encode = LazyEncoder().encode

class CKEditorWidget(forms.Textarea):
    """
    Widget providing CKEditor for Rich Text Editing.
    Supports direct image uploads and embed.
    """

    class Media:
        js = (
            JS('ckeditor/ckeditor-init.js', {
                'id': 'ckeditor-init-script',
                'data-ckeditor-basepath': getattr(
                    settings,
                    'CKEDITOR_BASEPATH',
                    static('ckeditor/ckeditor/'),
                ),
            }),
            'ckeditor/ckeditor/ckeditor.js',
        )

    def __init__(self, config_name='default', extra_plugins=None, external_plugin_resources=None, *args, **kwargs):
        super(CKEditorWidget, self).__init__(*args, **kwargs)
        # Setup config from defaults.
        self.config = DEFAULT_CONFIG.copy()

        # Try to get valid config from settings.
        configs = getattr(settings, 'CKEDITOR_CONFIGS', None)
        if configs:
            if isinstance(configs, dict):
                # Make sure the config_name exists.
                if config_name in configs:
                    config = configs[config_name]
                    # Make sure the configuration is a dictionary.
                    if not isinstance(config, dict):
                        raise ImproperlyConfigured('CKEDITOR_CONFIGS["%s"] \
                                setting must be a dictionary type.' %
                                                   config_name)
                    # Override defaults with settings config.
                    self.config.update(config)
                else:
                    raise ImproperlyConfigured("No configuration named '%s' \
                            found in your CKEDITOR_CONFIGS setting." %
                                               config_name)
            else:
                raise ImproperlyConfigured('CKEDITOR_CONFIGS setting must be a\
                        dictionary type.')

        extra_plugins = (
            extra_plugins
            or self.config.pop("extra_plugins", None)
            or []
        )

        if extra_plugins:
            self.config['extraPlugins'] = ','.join(extra_plugins)

        self.external_plugin_resources = (
            external_plugin_resources
            or self.config.pop("external_plugin_resources", None)
            or []
        )

    def render(self, name, value, attrs=None, renderer=None):
        if renderer is None:
            renderer = get_default_renderer()
        if value is None:
            value = ''
        final_attrs = self.build_attrs(self.attrs, attrs, name=name)
        self._set_config()
        external_plugin_resources = [[force_text(a), force_text(b), force_text(c)]
                                     for a, b, c in self.external_plugin_resources]

        return mark_safe(renderer.render('ckeditor/widget.html', {
            'final_attrs': flatatt(final_attrs),
            'value': conditional_escape(force_text(value)),
            'id': final_attrs['id'],
            'config': json_encode(self.config),
            'external_plugin_resources': json_encode(external_plugin_resources)
        }))

    def build_attrs(self, base_attrs, extra_attrs=None, **kwargs):
        """
        Helper function for building an attribute dictionary.
        This is combination of the same method from Django<=1.10 and Django1.11+
        """
        attrs = dict(base_attrs, **kwargs)
        if extra_attrs:
            attrs.update(extra_attrs)
        return attrs

    def _set_config(self):
        lang = get_language()
        if lang == 'zh-hans':
            lang = 'zh-cn'
        elif lang == 'zh-hant':
            lang = 'zh'
        self.config['language'] = lang
